FIG. 1 depicts a conventional tunneling magnetoresistive (TMR) element 10. The conventional TMR element 10 includes a seed layer 12, an antiferromagnetic (AFM) layer 14, a conventional pinned layer 16, a conventional barrier layer 18, a conventional free layer 20, and a capping layer 22. The conventional pinned layer 16 may a synthetic pinned layer including two ferromagnetic layers (not shown) separated by a nonmagnetic conductive spacer layer (not shown) that is typically Ru. Similarly, the conventional free layer 20 be a multilayer structure including, but not limited to a synthetic free layer including two ferromagnetic layers (not shown) separated by a nonmagnetic conductive spacer layer (not shown) that is typically Ru.
FIG. 2 depicts a conventional method 30 for providing the conventional TMR element 10. The seed layer 12 and AFM layer 14 are provided, via steps 32 and 34, respectively. The pinned layer 16 is formed, via step 36. Step 36 might include fabricating a synthetic pinned layer. The conventional barrier layer 18 is fabricated in step 38. Typically, step 38 includes depositing a metallic layer, such as Al, and completely oxidizing the metal in an oxygen environment to form a tunneling barrier. The free layer 20 is fabricated in step 40. The capping layer 22 is provided, via step 42.
Using the conventional method 30, the conventional TMR element 10 can be fabricated. One of ordinary skill in the art will readily recognize that it is desirable for the conventional barrier layer 18 to be on the order of ten Angstroms in thickness or less for current device applications. However, at such thicknesses of the conventional barrier layer 18, the conventional TMR element 10 may have an RA (resistance multiplied by cross-sectional area) that is too high for device applications. In particular, the TMR element 10 may have an RA on the order of one thousand Ohm-micrometers squared for a conventional barrier layer 10 on the order of nine to ten Angstroms. Furthermore, for conventional barrier layers 18 having a smaller thickness, the TMR effect may disappear. For example, some conventional TMR elements having a conventional barrier layer 18 that is seven Angstroms thick do not exhibit TMR. It is believed that the loss of TMR in such a thin conventional barrier layer 18 is due to defects, such as pinholes, which adversely affect the insulating nature of the conventional barrier layer 18. Consequently, the signal from such TMR elements is poor.
FIG. 3 depicts another, more recently developed method for providing a conventional TMR element. Thus, the method 50 is described in the context of the conventional TMR element 10. The conventional seed layer 12 and conventional AFM layer 14 are provided, via steps 52 and 54, respectively. The conventional pinned layer 16 is also fabricated, via step 56. Steps 58, 60, 62, and 64 are used to form the conventional barrier layer 18. A first metallic layer is deposited, via step 58. The thickness of this first metallic layer is less than the total thickness of the metal needed to form the conventional barrier layer 18. This first metallic layer is then oxidized in an oxygen environment, via step 60. Thus, a first portion of the conventional barrier layer 18 is fabricated. A second metallic layer is deposited, then oxidized in an oxygen environment, via steps 62 and 64, respectively. Upon completion of step 74, the conventional barrier layer 18 has been fabricated. The free layer 20 is fabricated in step 66. The capping layer 22 is deposited, via step 68.
Using the more recent method 50, a conventional TMR element 10 can be fabricated. For the conventional barrier layer 18 formed using the method 50 and having a thickness of as low as seven Angstroms, TMR is still exhibited. Moreover, the resulting conventional barrier layer 18 has a lower RA. Although the method 50 functions well for its intended purpose, one of ordinary skill in the art will readily recognize that even lower RA is desired for device applications.
Accordingly, what is needed is a method and system for providing a TMR element having a lower RA that still exhibits a sufficient signal.